The Census Bureau is using nearly one in three households in the District and Montgomery County as test subjects so it can figure out how best to use technologies in future census counts. With July 1 as a fixed reference date, residents will be asked to go online to answer a short series of questions about their race, gender, age, household size whether they're renters or homeowners.

This is the first large-scale field test designed to see how the internet and mobile phones can be employed in ways that could shave as much as $5 billion off the tab for the decennial count in 2020. The Census Bureau also is experimenting with getting information from administrative records kept by government agencies like Social Security and the IRS, in cases when people don't respond.